1equivalent to the product of three and five; one more than fourteen, or five more than ten; 15:all fifteen bedrooms have private facilitiesfifteen feet highfifteen of Howard’s troops were killed (Roman numeral: xv or XV)
a size of garment or other merchandise denoted by fifteen.
fifteen years old:she must be fifteen by now
a team of fifteen players, especially in rugby.
(15)British (of a film) classified as suitable for people of 15 years and over.
2 (the Fifteen) historical the Jacobite rebellion of 1715.
fifteen minutes of fame (or famous for fifteen minutes)
used with reference to a brief period of fame enjoyed by an ordinary person.
[from a remark made by Andy Warhol in 1968, predicting that in the future, everyone would be ‘world famous for fifteen minutes’]